Chemical pretreatment of coal in a stirred ball mill. Fossil energy quarterly report, 1 January 1989-31 March 1989.

摘要

The results of using a reducing agent (sodium dithionite) as an additive during the grinding and beneficiation of an Illinois No. 6 run-of-mine coal are shown. Earlier work had indicated that with use of the additive improved sulfur removal from Upper Freeport and Lower Kittanning run-of-mine coals could be achieved using physical beneficiation techniques such as oil agglomeration and microbubble flotation. For the best results with the earlier coal samples, it was seen that the additive had to be present both during grinding and separation for Upper Freeport coal, and during grinding only for Lower Kittanning coal. For the Illinois No. 6 coal used in this study, the results are sensitive not only to the stage in which the additive is added, but also to the type of separation technique used. It is evident that the additive does cause a depression of sulfide minerals, and thus improves sulfur removal, both during microbubble flotation and oil agglomeration. However, although the additive has no detrimental effects on the recovery of clean coal or ash reduction during oil agglomeration, significant decreases in coal recovery and ash reduction are observed if the additive is used in microbubble flotation. The possible reasons for this difference are discussed. 7 refs., 3 figs., 2 tabs. (ERA citation 15:046343)